Method of making a universal joint



June 21, 1960 cs. H. CORK 2,941,287

METHOD OF MAKING A UNIVERSAL JOINT Original Filed Aug. 19, 1953 3Sheets-Sheet 1 z I I June 21, 1960 G. H. CORK 2, 1,287

METHOD OF MAKING A UNIVERSAL JOINT Original Filed Aug. 19, 1953 3Sheets-Sheet 5 U'nitecl tate tent Ofice 2,941,287, Patented June 21,1960 METHOD OF MAKING A UNIVERSAL JOINT Gordon H. Cork, Detroit, Michassignor to Process Gear and Machine Company, Detroit, Mich, acorporation of Michigan Original application Aug. 19, 1953, Ser. No.375,261, new Patent No. 2,780,080, dated Feb. 5, 1957. Divided and thisapplication Nov. 26, 1956, Ser. No. 624,248

9 Claims. (Cl. 29-404) This invention relates to improvements in amethod of making a universal joint, and more particularly to a method ofmaking a universal joint of the so-called ball and socket type, althoughthe invention, as to its fundamental principles, might be utilized inthe making of universal joints of other types, as will be apparent toone skilled in the art.

The instant application is a division of my copending application,entitled Universal Joint, filed August 19, 1953, Serial No. 375,261, nowissued in Patent No. 2,780,080, dated FebruaryS, 1957.

In the past, many and various types of universal joints have beendeveloped, and likewise many and various methods of making them. Themost popular of these formerly known joints, insofar as usage is isconcerned, is the Hookes or cross-type joint. While that joint isobjectionable for numerous reasons, its popularity in use was due to itseconomy of construction in comparison with more eflicient joints. Thecross-type joint is clearly the farthest away from constant velocity ofsubstantially any type of universal joint; it is lacking in efliciency;it has little grease capacity; it has poor load carrying capacity; ithas considerable back lash; and the method of making it, whether theyoke members be forged or cast, requires a number of expensive machiningoperations. Some socalled constant velocity universal joints have beendeveloped, of which the Rzeppa and the Weiss joints are more commonlyrecognized as the most accurate in that regard. The method of makingthose joints, however, is prohibitively expensive for any common orreasonable commercial usage, and particularly so in the farm machineryand automotive fields of endeavor. The method of making those constantvelocity joints heretofore known requires numerous highly expensivemachining operations since the tolerance is a minimum, and involves anexceedingly expensive assembly operation due to the great number ofparts utilized in such joints.

Some universal joints of the so-called ball and socket type haveheretofore been attempted, at least to the constructive reduction topractice stage. That is, certain patents have been issued upon them.However, those joints embodied a socket on the end of one shaft, and ahead or knuckle, the so-called ball, on the end of the other shaft andboth the socket and the ball were complementally polygonal incross-section and in certain instances the socket had plane facesinside. However, each face of the knuckle was curvate about some radius,and'in some instances the knuckle was curvate both laterally andlongitudinally of each face, but again about some predetermined radius.As a consequence, devices of this character never proved practicalexcept in rare instances for a purpose that should properly bedesignated a shaft coupling, where the deviation between the shafts wasa matter of a degree or two. Not any of these devices were capable offunctioning as does the commonly known universal joint and permit anangle between the shafts in excess of a few degrees, and particularlydid not permit any such angle up to 45 degrees. The method of 2 makingthese knuckles or universal joint members was obviously merely agrinding operation or the equivalent to contour the joint faces inaccordance with'a predetermined radius. Such joints were clearly notconstant velocity joints in any real sense of the word.

With the foregoing in mind, it is an important object of the instantinvention to provide a simple and economical method of making one memberof a universal joint, the resultant joint carrying more load, andoperatingfar more efiiciently than any joint as economically constructedheretofore.

Another object of the invention is the provision of a method of making auniversal joint member which results in the provision of a universaljoint that may be sold in competition with the most economical andinefficient form of universal joint now accepted by the trade, and yetthe method results in the provisionof a universal joint which comparesfavorably in operation with the expensive constant velocity joints.

Still another object of the instant invention is the provision of amethod of making a universal joint member having working faces that arevariably curvate in both directions and conjugate to aplane.

Also an object of this invention is the provision of a method of makinga universal joint member having a plurality of working faces each ofwhich is generated during manufacture in keeping with the ultimatemovement of the joint member in actual operation.

A further feature of the instant invention is the provision of a methodof making the knuckle element for a universal joint of the ball andsocket type, which includes simulating the ultimate operating movementof the knuckle member during the cutting of the working faces thereon.

Still another object of the instant invention resides in the provisionof a method of making a series of universal joint members, by firstmaking a pattern member, including cutting the working faces of thepattern member while moving the member in simulation of the ultimatemovement of a joint member, making a mold from such pattern member, andthen successively casting the series of joint members from that mold.

While some of the more salient features, characteristics and advantagesof the instant method have been above pointed out, others will becomeapparent from the following disclosures, taken in conjunction with theaccompanying drawings, in which:

Figure 1 is a fragmentary part sectional, part elevational viewillustrating a universal joint made in accordance with the instantmethod;

Figure 2 is an end elevational view of the socket member of the jointproduced by the instant method;

Figure 3 is an end elevational view of the knuckle member made by theinstant method, and diagrammatically indicating proportional dimensions;

Figure 4 is a side elevation of the knuckle member, alsodiagrammatically indicating proportional dimensions";

Figure 5 is a transverse vertical sectional view taken substantially asindicated by the line VV of Figure 4 looking in the direction of thearrows, and also diagrammatically indicating proportional dimensions;

Figure 6 is a fragmentary part elevational, part sectional viewillustrating a step in the practice of the instant method;

Figure 7 is a view similar in character to Figure 6, but illustratingparticularly the practice of the method involved in this invention;

Figure 8 is a transverse vertical sectional view of a universal joint ofsomewhat different construction, but also capable of being made by theinstant method; and

Figure 9 is a fragmentary part sectional, part elevaing of the instant'several definitions of the meanings of words used herem asinas'r 3tional view illustrating the method of making the knuckle member of thejoint shown in Figure 8.

As shown on the drawings: 7 'For purposes of clarity, and also betterunderstand- I will at this point give invention,

and in the appended claims.

The term generate is herein used in the sense it is most generally-usedin connection with gear teeth, to indicate forming with theoreticalaccuracy, and not merely shaping to a preconceived radius or otherdimension.

The *angle of generation or generated angle" signifies'the maximum angleof deviation of one shaft from direct alignment with the other shaft forwhich the joint is initially designed; For example, the angle X seen inFigure l is the generated angle, assuming that the maximum deviationfrom shaft alignment at which the joint will successfully operate isthere present.

The term conjugate is also used in the sense that is most frequentlyused in connection with gear teeth, to signify that one part will drivethe other part or be driven thereby with a constant velocity ratio.

Where the term cone angle is, used in explaining the method of providingcontact faces, that is to be considered the angle at the apex of a conebetween diametral- 1y opposed elements of the cone, and that angle willbe twice the angle of generation.

It is apprehensible that the generated surfaces pro duced by the instantmethod and hereinafter discussed may be on one or the other members ofthe joint, that is, within the socket member or on the knuckle member,and herein and in the appended claims the invention is not to beconsidered limited to either member specifical- 1y, especially withregard to the broad aspects of the invention. Usually it will be foundmore convenient and more economical to provide the generated surfaces onthe knuckle member, with plane faces in the socket memher, and theinvention is so set forth herein. v

It will be also understood that with a universal joint made inaccordance with the instant method, it makes no difference if either thesocket or the knuckle is .the driven member, while the other is thedriving member.

In Figure l I have illustrated a universal joint of the ball and sockettype, of which the knuckle member has been manufactured in accordancewith the instant meth- 0d. The universal joint comprises in general asocket 1 in which is disposed the head or knuckle 2 of a knuckle membercomprising both the head and a stem or neck 3. The socket 1 may bewelded or equivalently secured to the end of a shaft coupling 4 which,to all intents and purposes, may be considered the shaft itself. Theneck 3 of the knuckle 2 may be equivalently firmly secured to the end ofa hollow torque shaft 5. As seen clearly in Figure l, the neck 3 ispreferably narrow so that the parts of the joint may be assembled in aconfined space and at a sharp angle to each other.

' The socket 1 is preferably polygonal in cross-section, and has aplurality of plane interior faces 6, as seen in Figure 2. The knuckle 2or ball is also polygonal in cross-section complementally to the socketmember, and preferably intimately fits within the socket member. Aspring ring or the equivalent 7 seated in a suitable groove in the endof the socket member may be utilized to prevent unintentional removal ofthe knuckle from the socket. Where there is a universal joint at eachend of the torque shaft 5, it may be desirable to utilize a conicalshaped compression spring 8 within the socket with the apical end of thespring seating centrally in the apex .of -.a conical recess 2a in theknuckle 2, so as to eliminate undue wear. This spring also maintains thetorque rod in a position of balance between a pair of universal joints,and it is not necessary to spline any of the shafts adjacent the jointssince the knuckle may move backwardly and forwardly in the socket. Theentire joint may be enclosed in a flexible boot 9 of synthetic rubber orequivd alent material, which may be secured to each respective shaft inany suitable manner.

In Figure l the joint is shown with the shafts at a definite angle toeach other. The angle X between the shafts may be the angle for whichthe faces on the knuckle 2 were generated, and if so, then the joint isillustrated in the maximum angular position of operation, but obviouslythe joint will operate at any angle between the angle X and zero degreesor shaft alignment.

For purposes of clarity, several important charactertistics of theknuckle 2 will next be described. Since the socket is illustrated as afour sided polygon with four plane interior faces 6, the knucklelikewise will be provided with four faces 10 and, as will later appear,the knuckle may have slightly rounded corners. It should be noted,however, that the number of faces in the socket and on the knuckle isnot critical. Usually, for ease of manufacture and durability there willbe between 3 and 8 faces on these members, since an odd number functionsthe same as an even number.

Since, in operation, the center point of each face on the knuckle orball does little or no work whatever, that center portion is preferablyslightly recessed as indicated at 11 (in an exaggerated showing) topermit the passage of lubricant from one side of the knuckle to theother when the knuckle moves backwardly and forwardly inside the socket.This prevents the knuckle from acting as a piston and ensures adequatelubrication at all times.

As a result of the generation process for forming the faces on theknuckle, hereinafter described, these faces are not cylindrical. Thefaces might be described, for want of better terms, as variably curvatein both directions. That is, each face is generally curvate laterally ofthe knuckle and longitudinally of the knuckle, but in no case does thecurvature follow the arc of a true circle and the curvature in variousportions of a knuckle face is not the same as the curvature in otherportions of that face.

As a result, it is substantially impossible to properly illustrate theexact character of a face on the knuckc. However, in Figures 3, 4 and 5,in order to make as full as possible a disclosure herein, I have set upproportionate dimensions of the knuckle that have proven satisfactoryfor a knuckle having an angle of generation of 30 Obviously, thesedimensions will vary for knuckles generated for a different angle.Likewise, actual dimensions of the knuckle and socket will vary inaccordance with the amount of load the joint is to carry, andaccordingly these dimensions are herein designated only proportionately.

As seen best in Figures 3 and 4, the maximum width of the knuckletransversely to its shaft axis is indicated by W, and this is the widthfrom the high center point of one face to the high center point of anopposite face,

before the lubr cant-passing recesses .11 have en pro,-

vided. Moving over half-way to the edge along the center of the face, adistance of AW, the dimension W1 will be approximately 99.6% of W. Atthe side edge of the joint. another movement of AW, there is adimensionWZ which is approximately 98.9% of W.

Dimensions at the forward and rear edges of the knuckle will be the same.and with reference more particnlarly to Figure 3, it will seem that theWidest dimension at the forward edge, designated L, isapproxirnately 91%of W. Half-way to the side along this forward edge there is thedimension Ll which is approximately 89% of W; and at the edge there isthe dimension L2 which is approximately 8 6.6% of W.

Now in reference to Figure 4, the dimension T indicates the thickness ofthe knuckle, and that dimension is not a constant nor is it proportionalto the dimension W. That is because thicknesses of knuckles will withthe angle of generation, in that a small angle of generation does notrequire much thickness to have proper contact with the faces of thesocket, whereas a larger angle of generation requires a thicker knuckle.In Figure 4 the section line designating the location of Figure 5 istaken half-way from the center of the face to the forward edge of theface, or iT.

In Figure 5, the dimension M indicates the maximum width of the knucklehalf-way between the forward edge and the center and this dimension M isapproximately 9 7% of W. Halfway between M and the adjacent side edge ofthe knuckle, a distance of AM, there is the dimension M1 which isapproximately 96.4% of W; and at the edge the dimension M2 isapproximately 94% of W.

As stated above, the aforesaid proportional dimensional relationshipsare approximate, due allowance being taken for mechanical errors, etc.,and they are given herein for the purpose of indicating the generalcharacter of the faces on the knuckle. However, it is not necessary inthe manufacture of the universal joint for these particularproportionate dimensions to be known to the operator, because if thefaces on the knuckle are generated in the manner hereinafter described,the joint will operate, whether or not the operator has any ideaconcerning the resultant proportional dimensions.

During the making of the knuckle 2, it is preferably initially formed toapproximately the desired size and shape, by forging or in equivalentmanner, in order to reduce as much as possible the cutting operation onthe faces during the generation of these faces. The faces may begenerated one at a time, if so desired, but I have illustrated inFigures 6 and 7 an arrangement whereby all of the faces may be generatedat the same time. To this end, there are provided four identical cuttingmeans, each comprising a driving element such as a motor 12, a shaft 13,and a cutting tool 14. Each cutting tool is preferably of substantiallyhourglass shape and includes a pair of truncated conical cutting members15' and 16 with a spacer element 17 disposed therebetween, if sodesired. With cutting elements of this shape, the aforesaid slightlyrounded corners, indicated at 18 are provided on the knuckle, but theseslightly rounded corners do not interfere in any manner with theoperation of the joint.

Preferably, the cutting elements 15 and 16 for each tool provide astraight line out or cutting contact against the knuckle 2, and withthis arrangement each cutting element 15 and 16 generates /2 a face onthe knuckle. It is not necessary for any tool to cut in the vicinity ofthe lubricant-passing recess 11 in each face of the knuckle, although itwill be understood that if a recess is not desired, a single cuttingtool may generate an entire face.

During the generation of the faces, a cutting tool does not move exceptby way of rotation on its own axis. The knuckle is held in any suitablemanner against rotation about its own axis, and by any other suitablemechanism the knuckle is bodily gyrated or oscillated so that its axisdefines an imaginary cone, indicated by the dotted line 19 in Figure 7,the apex of this imaginary cone being preferably at the center of theknuckle or ball 2, although in some instances that particular locationmay not be essential. The cone angle of the imaginary cone will be twicethe generated angle of the knuckle, so that half the cone angle is themaximum angle of deviation from shaft alignment for which thatparticular knuckle is intended to operate satisfactorily. The generatedangle may be anything desired from zero degrees to 45 degrees.

It will be especially noted that by this method of forming the knucklefaces, each face is generated-conjugately to a plane surface, the linecontact with the cutting element acting as the plane surface. Duringgeneration, the

knuckle is given a movement in simulation of the movement it will havein actual usage. Therefore, assuming perfection in the mechanical work,a joint of the character illustrated herein must provide constantvelocity at the generated angle, as well as at zero degrees. The jointmay vary slightly, and in most cases that will be but a very slightvariation, from constant velocity at angles intermediate zero degreesand.the generated angle. That slight variance from constant velocity insuch intermediate region may be considerably reduced by providing morefaces on the knuckle.

It will be noted, therefore that the knuckle will operate smoothlyagainst the plane faces in the socket member, whereas a knuckle havingfaces defined by true curvature around a predetermined center wouldcause a fracture of the joint in a single'revolution if the deviationfrom shaft alignment was, more than one or two degrees.

In the event the knuckle is the joint member provided with the generatedfaces, as herein set forth, the socket -1 need be only a stamping or adrawing of suflicient accuracy to provide substantially plane interiorfacesfor the knuckle to operate against.

In Figures 8 and 9 I have illustrated a method of forming a knuckle 20having a stem 21, which may be termed a knuckle with 8 faces, each facebeing fluted or angled inwardly to a lubricant-passing recess 22. Thisknuckle will operate satisfactorily within a fluted socket I23,- shownin Figure 8.

The knuckle 20 is generated in substantially the same manner as thepreviously described knuckle 2. However, different tools are required.To this end, four sets of generating mechanism or cutting tools aredisclosed, each set including a motor 24, a shaft 25, and a cutting tool26. Each cutting tool 26 consists of a pair of confronting urn-shapedcutting elements 27 and 28 separated by a suitable spacer 29therebetween. Each such cutting tool will generate the sum total of twofaces on the knuckle, including one complete inwardly angled face andonehalf each of two adjacent faces. During the generation of the faceson the knuckle 20, the knuckle is held against rotation and gyrated oroscillated about its axis to provide a desired angle of generation, inthe manner above described.

The instant invention also contemplates the molding or casting ofuniversal joint members, such method perhaps being more desirable forquantity production. In such event, a pattern member would be generatedin the manner above described, and a mold made from that pattern member.Then, a series of joint members might be molded, cast, die cast, orequivalently made from the molds or dies resulting from the patternmember. Such process is sufliciently known in the art as not to warrantillustration of the dies or molds herein.

It may be mentioned that for agricultural machinery and the like, aknuckle with four faces is quite sufficient and satisfactory, and formost uses of universal joints, including automotive vehicles, a knucklehaving four or six faces is quite satisfactory, with substantiallyconstant velocity resulting. In any event, the deviation from trueconstant velocity would not be material. The structure indicated inFigures 8 and 9 would be most frequently used for more specialized andaccurate machinery where the cost of the universal joint would besecondary in consideration, and constant velocity desired to a closertolerance. While the difference in manufacturing cost between theproduction of the knuckle 2 and theknuckle 20 is not very great by thepractice of the instant invention, yet even a slight different in costis almost paramount in highly competitive fields of endeavor such as theautomotive industry.

From the foregoing, it is apparent that I have provided a method ofmaking a universal joint that is extremely simple and economical topractice, requires the use of only economical and long lastingmechanism, and which results in the provision of a universal jointhighly eflicient in operation and closely approaching constant velocitythroughout the angle of generation.

It will be understood that modifications and variations may beelfectedwithout departing from the scope of the novel concepts of thepresent invention.

I claim:

1. The method of making the knuckle member for a universal joint of theball and socket type wherein the socket has. a plurality of planefaces,including the steps of roughly forming a knuckle member with an equalnumber of working faces, and then finishing each face of the knucklemember by oscillating the same against a cutting tool in a manner toinclude all angular bearing relationships said working face willultimately assume in operation of the joint. 7

2. The method of making a universal joint member with the aid of acutting tool, including the steps of generating a face on the jointmember by oscillating the joint member with its axis describing aconical path of which the cone angle is twice the intended maximum angleat which the member is to ultimately operate, holding the member againstrotation about its axis, and applying a cutting tool-to the face of themember with the tool rotating about its axis but otherwise heldstationary.

3. The method of generating the knuckle member of a universal joint ofthe ball and socket type, including the steps of spinning a cutterhaving a straight line cutting contact on its axis and holding thecutter otherwise stationary, oscillating a face of the knuckle againstthe cutter by moving the knuckle so its axis defines a cone having acone angle twice the angle for which the knuckle is being generated, andholding the knuckle against rotation about its axis.

4. The method of making the knuckle member of a universal joint of theball and socket type, wherein the socket has a plurality of plane insidefaces, including the stepsof providing an equal number of faces on theknuckle member, and then contouring each face of the knuckle member byplacing it against a cutting tool and oscillating the knuckle member soits axis will outline a right cone while holding the knuckle againstrotation about its axis.

5. The method of making the knuckle member of a universal joint of theball and socket type, wherein the socket has a plurality of plane insidefaces, including the steps of providing an equal number of faces on theknuckle member, placing all the faces of the knuckle member againstrotating cutting tools, and oscillating the knuckle member so its axisdefines a cone having an apex at the center of the knuckle while holdingthe knuckle member against rotation about its axis.

6. The method of making the knuckle member of a universal joint of theball and socket type, wherein the socket has a plurality of plane insidefaces, including the steps of providing an equal number of faces on theknuckle member, placing all of the faces of the knuckle member againstrotating cutting tools and simultaneously grinding said faces whilebodily oscillating the knuckle member so its axis defines a cone havingan apex at the center of the knuckle and holding the knuckle memberagainst rotation about its axis, and wherein the angle betweendiarnetrally opposed elements at the apex of the cone is twice the anglefrom shaft alinement for which the universal joint is intended. 1

7. The method of generating a working face on on member of a universaljoint, including the steps of holding the member against rotation aboutits axis, and oscillating the member bodily against a cutting tool in amanner to include all angular bearing relationships said working facewill ultimately assume in operation of the joint.

8. The method of generating a working face on one member of a universaljoint, including the steps of holding the member against rotation aboutits axis, and oscillating the member bodily against a cutting tool in amannet to include all angular bearing relationships said working facewill ultimately assume in operation of the joint, and then using saidmember in the making of a mold from which to cast other joint members.

9. The method of generating the knuckle member of a universal joint ofthe ball and socket type, including the steps of spinning a cutterhaving a straight line cutting contact on its axis and holding thecutter otherwise stationary, oscillating a face of the knuckle againstthe cutter by moving the knuckle so its axis defines a cone having acone angle twice the angle for which the knuckle is being generated, andholding the knuckle against rotationabout its axis, and then using thegenerated knuckle member as a pattern from which to make a mold to castother similar knuckle members.

References Cited in the file of this patent UNITED STATES PATENTS1,674,753 Witter June 26, 1928 1,770,502 Weiss July 15, 1930 1,985,531Swenson Dec. 25, 1934 2,055,421 Weiss Sept. 22, 1936 2,304,666 SturgessDec. 8, 1942 2,394,890 Blomgren Feb. 12, 1946 2,425,809 Johnson Aug. 19,1947 r imma-

